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Investigation of Ionizing Radiation Infuence to the Communication Systems of Satellites
Golubev, Martin ; Kubíček, Michal (referee) ; Katovský, Karel (advisor)
This master thesis discuss about ionizing radiation, interaction with matter and effects on her. In the work is discussed differend types of interactions of directly ionizing radiation and indirectly ionizing radiation. Below is an overview of methods of shielding from all of types of ionizing radiation. Second part of this thesis discuss about single event effects in semiconductors which are cause by ionizing radiation. At the end is described design of measuring instrument included FPGA chips. This design is discused both from point of wiew hardware and software too.
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Investigation of Ionizing Radiation Infuence to the Communication Systems of Satellites
Golubev, Martin ; Hobst, Leonard (referee) ; Katovský, Karel (advisor)
This master thesis discuss about ionizing radiation, interaction with matter and effects on her. In the work is discussed differend types of interactions of directly ionizing radiation and indirectly ionizing radiation. Below is an overview of methods of shielding from all of types of ionizing radiation. Second part of this thesis discuss about single event effects in semiconductors which are cause by ionizing radiation. At the end is described design of measuring instrument included FPGA chips. This design is discused both from point of wiew hardware and software too.
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Empirical modeling of the location of the Earth's magnetopause
Machková, Anna ; Němec, František (advisor) ; Grygorov, Kostiantyn (referee)
This bachelor thesis focuses on suggesting possible improvements of the existing models of the magnetopause stand-off distance, i.e., on identification of the parameters which are not properly (or not at all) included. Magnetopause is a border between the terrestrial and interplanetary magnetic fields, where the pressure of the Earth's magnetic field balances the solar wind dynamic pressure. In order to analyze the parameters, which have an influence on the magnetopause radial distance, we perform a systematic study of an existing database of 16800 magnetopause crossings registered by 8 different satellites. We focus on the effect of the topology of the terrestrial magnetic field, which is not perfectly dipolar, and whose values close to the subsolar point exhibit significant diurnal and annual variations. Another analyzed phenomenon is the magnetospheric ring current and its influence on the magnetic field strength near the magnetopause. Possible changes of this magnetic field have a direct influence on the magnetopause distance from the Earth. Attention is also devoted to the potentially different positions of the magnetopause at the times of fast and slow solar wind. Finally, we discuss complications related to the satellite orbits and the resulting uneven spatial distribution of the used data set.
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Turbulence in the solar wind from inertial to kinetic scales
Pitňa, Alexander ; Šafránková, Jana (advisor) ; Hellinger, Petr (referee) ; Kulhánek, Petr (referee)
Solar wind, a stream of supersonic plasma emanating from the solar corona, serves as an ideal laboratory for a study of high Reynolds number plasma flows. Turbulent processes that govern the dynamics of the so-called inertial range, i.e., the spatial scales smaller than energy injection scales but larger than the scales where the dissipation processes set in, have been studied for decades. At present, it is believed that the large-scale free energy in a form of kinetic and magnetic fluctuations is transferred via turbulent cascade into smaller scales, where kinetic effects become dominant and heating takes place. In order to understand dissipation processes, high-cadence measurements of solar wind parameters are necessary. The bright monitor of the solar wind (BMSW) instrument on board the Spektr-R spacecraft provides such data, and in tandem with high-cadence measurements of the magnetic field from the Wind spacecraft, we are able address the nature of the sub-ion scale fluctuations. The thesis focus on three interconnected topics, (a) what changes are induced by the passage of a collisionless IP shock in the framework of turbulence, (b) study of a decay of the turbulent energy downstream an IP shock, and (c) identifying the dominant mode of the sub-ion scale fluctuations.
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Variations of solar wind parameters through solar cycle
Turčičová, Marie ; Šafránková, Jana (advisor) ; Ďurovcová, Tereza (referee)
Statistical analysis of data from satellites that operate in the vicinity of the Sun can partly contribute to the elucidation of complex processes around the Sun. This thesis is devoted to a long-term statistical study of particular parameters of the solar wind. We have used data from the Wind satellite, especially its measurements of the velocity, density and temperature of protons and α- particles. By using standard statistical tools, we explored their behaviour during the 23th and 24th solar cycles, including a comparison of both cycles. Our results are in accordance with other known studies.
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Solar wind helium abundance variations
Cagaš, Petr ; Šafránková, Jana (advisor) ; Enžl, Jakub (referee)
The thesis presents results of one-year measurements of solar wind helium ion abundance variations with the BMSW instrument on-board the SPEKTR-R spacecraft. The BMSW instrument was designed and built for fast measurements of the solar wind and can obtain a complete cumulative distribution function of solar wind particles every 1.5 s. A statistical study of the data shows that in spite of the current prevailing opinion, abrupt changes in the relative helium abundance do not correlate with the changes in other parameters of the solar wind and are therefore likely caused by in-transit turbulence that contributes to the solar wind heating and leads to rise of the solar wind temperature with the helium content.
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Development of UV detector for space applications
Kočiščák, Samuel ; Pavlů, Jiří (advisor) ; Jeřáb, Martin (referee)
Title: Development of UV Detector for Space Applications Author: Samuel Kočiščák Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Jiří Pavlů, Ph.D., Department of Surface and Plasma Science Abstract: It is not unusual that space measurement is influenced by UV irradia- tion causing photoemission on delicate electronic components. Therefore informa- tion on UV irradiance is very useful. Particularly useful is non-delayed, immediate quantitative information (on a time scales of seconds) identifying unexpected va- riation in the irradiance of such electronic parts. The goal was to construct a prototype, measure basic properties and discuss ca- pabilities of a detector capable of continuous measurement of UV irradiance of a spacecraft, working on the principle of photoemission alone. We have success- fully shown the capabilities of a prototype and established some of its key basic properties, e.g. their stability in cosmic environment. Keywords: VUV, Faraday cup, UV detector, UV transmittance, solar wind
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Magnetic reconnection in the solar wind
Enžl, Jakub ; Přech, Lubomír (advisor)
Magnetic reconnection is a fundamental process that changes magnetic field configuration and converts a magnetic energy to flow energy and plasma heating. It can be found in a plasma with frozen magnetic field lines at boundaries where different magnetic field topologies encounter each other and thin current sheets are created as it is typical in the solar wind. In the thesis, we have used spacecraft measurements of solar wind plasma and magnetic field to found magnetic reconnection exhausts. We analyze and compare them with theoretical predictions. The results of the statistical analysis oriented on re-distribution of the magnetic energy in reconnection showed that both a portion of the energy deposited into heat as well as the energy spent on an acceleration of the exhaust plasma increase with the magnetic shear angle in accord with the increase of the magnetic flux available for reconnection. Moreover, we identify unusual events in the solar wind; we found magnetic reconnection exhausts accompanied by one or two side jets and explained their possible causes.
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Role of Magnetosheath Parameters on Magnetopause Processes
Krupařová, Oksana ; Šafránková, Jana (advisor)
The thesis addresses of two regions significant for the solar wind-magnetosphere coupling: the cusp in high geomagnetic latitudes and the low-latitude (LLBL) subsolar magnetopause. A penetration of plasma of a solar origin into the magnetosphere could be realized directly through magnetospheric cusps. The region adjacent to the magnetopause in the cusp vicinity is highly turbulent, occupied by the heated magnetosheath-like plasma with a low drift velocity for which occurrence of vortices is a very common feature. In the first part of the thesis, we present a detailed analysis of a vortex-like structure created by a turbulent plasma flow around the magnetopause indentation above the cusp and using the data from Interball-1 and Magion-4; we find necessary conditions and a possible mechanisms to creation of such structures. The second part concerns the low-latitude boundary layer formation, its spatial structure and temporal changes based on THEMIS multipoint observations. In spite of its crucial role in transfer of mass, momentum, and energy from the solar wind into the magnetosphere, LLBL parameters and their relations to upstream conditions are still under debate. We demonstrate that sudden changes in upstream plasma and magnetic field parameters could lead to reformation of the spatial LLBL profile from...
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Multipoint observations of magnetospheric wave phenomena
Bezděková, Barbora ; Němec, František (advisor) ; Grison, Benjamin (referee) ; Shklyar, David R. (referee)
Electromagnetic wave phenomena represent a crucial factor during the forma- tion of the Earth's magnetosphere, as they are responsible for the energy trans- fer in the collisionless plasma medium. Multipoint observations of such wave phenomena are particularly useful to distinguish between spatial and temporal intensity variations. Moreover, an approximate event spatial extent and prop- agation directions can be determined. The thesis is focused on the statistical study of conjugate observations of wave phenomena called quasiperiodic (QP) emissions observed by the Van Allen Probes spacecraft and ground-based Kan- nuslehto station. Altogether, 26 simultaneously observed events were analyzed. This approach is unique in the sense that most such analyses up to date were only case studies. The thesis further presents the analysis of the dependence of properties of another wave phenomena, called magnetospheric line radiation (MLR), on the geomagnetic activity indices and solar wind parameters. Geomag- netic activity effects on the event characteristics are revealed. Finally, the effect of interplanetary shocks on the overall very low frequency (VLF) wave intensity measured by the DEMETER spacecraft is studied.
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